1. Field of the Invention
Various embodiments of the invention are directed to temperature compensated optical multiplexers. More particularly, embodiments of the invention are directed to a reflective arrayed waveguide grating multiplexer having a mirror that rotates based on differential thermal expansion to compensate for differences in index of refraction caused by temperature changes.
2. Discussion of the Related Art
Optical multiplexers may comprise waveguides within which light of varying frequencies is allowed to propagate. However, the index of refraction within the waveguides changes with operating temperature, which therefore changes the optical path lengths and adversely affects operation. In order to obviate the adverse effects of temperature, some related art systems attempt to precisely control the temperature of optical multiplexers. Precise temperature control may be difficult and costly, particularly in remote locations.
Other related art devices may attempt to compensate for temperature changes rather than perform temperature control. Published United States Patent Application No. 2002/0097961A1 to Kazarinov discloses such a system. In the Kazarinov system, a rigid mirror is rotationally fixed to the substrate upon which the waveguides are formed. The mirror is rotated as a function of temperature by a thermally conductive body, e.g. a copper block, pushing on the reflective surface. However, it is difficult to rotationally mount the mirror on the substrate, and further the thermally conductive body pushing on the reflective surface and the substrate tends to distort the mirror and produce stress in the grating, degrading performance.